The following priority applications, Japanese Patent Application No. Hei 6-162684, filed in Japan on Jun. 20, 1994; Japanese Patent Applicaton No. Hei 6-270374, filed in Japan on Oct. 6, 1994; and Japanese Patent Application No. Hei 6-312736, filed in Japan on Nov. 22, 1994 are hereby incorporated by reference into the present specification.
1. Field of the Invention
The present invention relates to a stereoscopic display which enables observation of stereoscopic images without wearing special glasses or the like.
2. Description of Related Art
The present inventor has already proposed one stereoscopic display (U.S. patent application Ser. No. 08/135,482). This device includes a color liquid crystal plate for displaying stereo-pairs composed of right and left eye perspectives in time-interlaced manner, a monochrome TV display for displaying face images of each observer, and a large convex lens for directing the right and left eye perspectives to respective right and left eyes of each observer based on the face images of the monochrome TV display.
This device enables simultaneous observation of stereoscopic images by plural persons without wearing special glasses. This device, however, has a problem in that the distance between the large convex lens and the monochrome TV display is large, because the large convex lens has a large focal length, thereby increasing the depth of the device undesirably.
It is an object of the present invention to provide a thin stereoscopic display having a reduced depth, which enables simultaneous observation of stereoscopic images by plural persons without wearing special glasses or the like.
The stereoscopic display in accordance with the present invention includes stereo-pairs display means for selectively displaying stereo-pairs composed of right and left eye perspectives to be observed by observers, observers"" face images display means for displaying observers"" face images adapted to direct stereo-pairs displayed by the stereo-pairs display means to right and left eyes of the respective observers with accuracy, and arrayed focusing means for directing the stereo-pairs displayed by the stereo-pairs display means to right and left eyes of each observer based on the observers"" face images displayed by the observers"" face images display means. The arrayed focusing means is situated on the plane from which it focuses observers"" optical images substantially on a screen of the observers"" face images display means in geometrical agreement with the observers"" face images displayed thereby.
In a first aspect of the invention, the stereo-pairs display means is composed of transparent type electro-optical spatial modulation elements disposed between the observers and the arrayed focusing means to display the stereo-pairs in time-interlaced state, and the observers"" face images display means is composed of a surface light source unit disposed behind the arrayed focusing means to display pairs of observers"" face images of which flashing regions are substantially inverted in time-interlaced manner. The transparent type electro-optical spatial modulation elements selectively use one of each pair of observers"" face images displayed by the surface light source unit as back light so as to be synchronized with the time-interlaced display thereof. Preferably embodiment, the surface light source unit is composed of a surface light source of which flashing regions are vdriable so as to be synchronized with the time-interlaced display of the electro-optical spatial modulation elements. More preferably, the surface light source unit is composed of at least one light source and transparent type electro-optical spatial modulation elements provided on a light emission side of the at least one light source.
In a second aspect of the invention, the stereo-pairs display means is composed of transparent type electro-optical spatial modulation elements disposed between the observers and the arrayed focusing means to display the stereo-pairs in time-parallel state, and the observers"" face images display means is composed of a surface light source unit which is disposed behind the arrayed focusing means to display pairs of observers"" face images of which polarization axes are oriented approximately 90xc2x0 with respect to each other. The transparent type electro-optical spatial modulation elements selectively use one of each pair of observers"" face images displayed by the surface light source unit as back light. In a preferred embodiment, the surface light source unit includes a surface light source of which variable regions for emitting light rays of polarization axes oriented approximately 90xc2x0 with respect to each other, or includes a surface light source of which variable flashing regions and a polarization plate of which polarization axes are oriented approximately 90xc2x0 so as to correspond to the displayed pairs of observers"" face images. In the latter case, the surface light source unit is composed of a monochrome liquid crystal TV display, and in the polarization plate of the monochrome liquid crystal TV display, two kinds of regions of which polarization axes are oriented approximately 90xc2x0 with respect to each other are distributed with uniformity.
In the second aspect of the invention, the transparent type electro-optical spatial modulation elements can be composed of a color liquid crystal image display plate wherein regions displaying left eye perspectives and those displaying right eye perspectives are alternately distributed with uniformity, and a polarizer on an input side thereof has such a member as to rotate polarization axes approximately 90xc2x0 so as to correspond to the above regions of the color liquid crystal image display plate.
In a third aspect of the invention, the stereo-pairs display means is composed of transparent type electro-optical spatial modulation elements disposed between observers and the arrayed focusing means to display stereo-pairs in time-parallel state, and the observers"" face images display means is composed of a surface light source unit disposed behind the arrayed focusing means to display pairs of observers"" face images of which flashing regions are substantially inverted in time-interlaced manner. The transparent type electro-optical spatial modulation elements selectively use one of each pair of observer""s face images displayed by the surface light source unit as back light so as to be synchronized with the time-interlaced display of the surface light source unit. In addition, an electro-optical spatial modulation element is further disposed between the surface light source unit and the spatial modulation elements for rotating the polarization axes of the pairs of observers"" face images displayed by the surface light source unit approximately 90xc2x0 so as to be synchronized with the time-interlaced display of the surface light source unit.
In a fourth aspect of the invention, the stereo-pairs display means is composed of transparent type electro-optical spatial modulation elements disposed between the observers and the arrayed focusing means to display the stereo-pairs in time-interlaced state, and the observers"" face images display means is composed of a surface light source unit disposed behind the arrayed focusing means to display pairs of observers"" face images of which polarization axes are oriented approximately 90xc2x0 with respect to each other. In addition, a transparent type electro-optical spatial modulation element is further disposed between the surface light source unit and the spatial modulation elements for rotating the polarization axes of the pairs of observers"" face images displayed by the surface light source unit approximately 90xc2x0 so as to be synchronized with the time-interlaced display by the transparent type electro-optical spatial modulation elements.
The stereoscopic display of the present invention can include taking means disposed in the vicinity of the arrayed focusing means for taking observers"" face images continuously.
In addition, the stereoscopic display of the present invention can include illuminating means disposed on at least one of right and left sides of the observers for illuminating observers"" faces from at least one side thereof.
In addition, the stereoscopic display of the present invention can include image modulation processing means for forming binary images based on the observers"" face images taken by the taking means, and inputting the formed binary images into the observers"" face images display means.
With the stereoscopic display in accordance with the present invention, by providing the arrayed focusing means on the plane from which it focuses observers"" optical images substantially on the observers"" face images display means in geometrical agreement with observers"" face images displayed thereby, the stereo-pairs displayed by the stereo-pairs display means in time-interlaced or time-parallel manner are directed selectively to left and right eyes of the respective observers with accuracy, while back-lit by the observers"" face images of the observers"" face images display means. Since the focusing means has an arrayed configuration of which the focal length is less than that of a conventionally used large convex lens, the overall size of device in the direction of depth can be reduced. Any person positioned within the area where observers"" optical images can be focused by the arrayed focusing means substantially on the screen of the observers"" face images display means can observe stereoscopic images. Furthermore, he or she can observe such stereoscopic images continuously while moving his or her observation position unless he or she is outside of the above area. In addition, plural persons can observe stereoscopic images simultaneously.
Other objects, features, and characteristics of the present invention will become apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification.